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Abstract:

A dilator retractor and the dilators that are used for minimally invasive
spinal surgery or other surgery are configured to accommodate the
anatomical structure of the patient as by configuring the cross sectional
area in an elliptical shape, or by forming a funnel configuration with
the wider end at the proximate end. In some embodiments the distal end is
contoured to also accommodate the anatomical structure of the patient so
that a cylindrically shaped, funnel shaped, ovoid shaped dilator
retractor can be sloped or tunneled to accommodate the bone structure of
the patient or provide access for implants. The dilator retractor is made
with different lengths to accommodate the depth of the cavity formed by
the dilators.

Claims:

1-12. (canceled)

13. A surgical method, comprising: inserting a non-cannulated dilator
into an incision in a patient's skin; forcing the non-cannulated dilator
through tissue of the patient until a distal tip of the non-cannulated
dilator reaches a target location in the patient; inserting a plurality
of cannulated dilators over the non-cannulated dilator to enlarge an
opening formed by the non-cannulated dilator, at least one of the
cannulated dilators having an ovoid cross-section.

14. The method of claim 13, wherein the plurality of cannulated dilators
includes a first cannulated dilator having a circular interior
cross-section and an ovoid exterior cross-section.

15. The method of claim 14, wherein the plurality of cannulated dilators
includes a second cannulated dilator having an ovoid interior
cross-section and an ovoid exterior cross-section.

16. The method of claim 15, wherein the method comprises inserting the
plurality of cannulated dilators such that the non-cannulated dilator is
disposed within the first cannulated dilator and the first cannulated
dilator is disposed within the second cannulated dilator.

17. The method of claim 13, further comprising removing the
non-cannulated dilator from the patient and removing all but an outermost
one of the plurality of cannulated dilators from the patient to form a
working channel to the target location, the working channel having an
ovoid cross-section.

18. The method of claim 13, wherein inserting the plurality of cannulated
dilators comprises inserting a plurality of cannulated dilators each
having a successively shorter length.

19. The method of claim 13, wherein the method comprises positioning a
sloped distal end of at least one of the cannulated dilators in contact
with a vertebra of the patient.

20. The method of claim 13, wherein the method comprises inserting at
least one cannulated dilator having a funnel-shaped proximal end.

21. The method of claim 13, further comprising positioning the at least
one cannulated dilator having an ovoid cross section such that a major
axis of said dilator extends parallel to the patient's spinal column and
a minor axis of said dilator extends transverse to the patient's spinal
column.

22. A dilator kit, comprising: a non-cannulated dilator having an
elongated cylindrical solid body with a tool engaging portion at a
proximal end thereof and a pointed tip portion at a distal end thereof; a
plurality of cannulated dilators, at least one of the cannulated dilators
having an ovoid cross-section.

23. The kit of claim 22, wherein each of the plurality of cannulated
dilators has a different length.

24. The kit of claim 22, wherein each of the plurality of cannulated
dilators has a beveled distal end that defines a sharp edge.

25. The kit of claim 22, further comprising an anvil that fits over a
proximal end of at least one of the cannulated dilators.

26. The kit of claim 22, wherein at least one of the cannulated dilators
has an angled distal end.

27. The kit of claim 22, wherein at least one of the cannulated dilators
has a funnel-shaped proximal end.

28. The kit of claim 22, wherein the plurality of cannulated dilators
includes a first cannulated dilator having a circular interior
cross-section and an ovoid exterior cross-section.

29. The kit of claim 28, wherein the plurality of cannulated dilators
includes a second cannulated dilator having an ovoid interior
cross-section and an ovoid exterior cross-section.

30. The kit of claim 29, wherein the non-cannulated dilator is sized to
be received within the first cannulated dilator and the first cannulated
dilator is sized to be received within the second cannulated dilator.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. application Ser. No.
14/475,161 (now U.S. Pat. No. ______) filed on Sep. 2, 2014 and entitled
"Configured and Sized Cannula," which is a continuation of U.S.
application Ser. No. 14/026,536 (now U.S. Pat. No. 8,852,244) filed on
Sep. 13, 2013 and entitled "Configured and Sized Cannula," which is a
continuation of U.S. application Ser. No. 13/728,172 (now U.S. Pat. No.
8,556,905) filed on Dec. 27, 2012 and entitled "Configured and Sized
Cannula," which is a continuation of U.S. application Ser. No. 13/523,033
(now U.S. Pat. No. 8,361,151) filed on Jun. 14, 2012 and entitled
"Configured and Sized Cannula," which is a continuation of U.S.
application Ser. No. 12/776,857 (now U.S. Pat. No. 8,235,999) filed on
May 10, 2010 and entitled "Configured and Sized Cannula," which is a
continuation of U.S. patent application Ser. No. 11/030,218 (now U.S.
Pat. No. 8,192,437) filed on Jan. 6, 2005 and entitled "Configured And
Sized Cannula," which is a divisional of U.S. patent application Ser. No.
10/021,809 (now U.S. Pat. No. 7,008,431) filed on Oct. 30, 2001 and
entitled "Configured And Sized Cannula," each of which is expressly
incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] This invention relates to medical instruments for use in surgical
procedures and more particularly to a wide-channel cannula that is
pre-sized, pre-configured and tailored to conform to the patient's
anatomy.

BACKGROUND OF THE INVENTION

[0003] In one aspect of this invention, the invention considers the
anatomical shape of the area of the patient being operated on and tailors
the shape of the dilators and the dilator retractor or cannula to
accommodate that shape. In another aspect of this invention, the
invention constitutes an improvement over the apparatus and method
disclosed and claimed in U.S. Pat. No. 6,159,179 granted on Dec. 12, 2000
to the inventor of this patent application and entitled "Cannula and
Sizing and Insertion Method" by providing different sizes of the same
configuration of dilator retractors.

[0004] As is well known by those skilled in this technology, the cannula
utilized in the field of minimally invasive surgery is particularly
efficacious in performing such spinal medical procedures as laminotomy,
medial facetectomy, foraminotomy, nerve root retraction, discectomy and
the like, is cylindrically shaped. I have found that a cylindrically
shaped cannula is not always ideal for certain surgical procedures and
this invention is intended to obviate the problems incidental to a
cylindrically shaped cannula and to increase the number of surgical
procedures that can be performed by dilation methods by changing the
configuration of the retractor tube or cannula. As is apparent to one
skilled in this technology, the anatomy of the human spine is not made up
of flat surfaces and a purely cylindrical device passed over cylindrical
dilators and directed toward the lamina more likely than not settles off
of or partly on the bone. When this occurs, a tuft of muscle migrates to
or is left between the bone and the bottom of the retractor and must be
removed surgically. Obviously, this surgery is a source of pain and
discomfort for the patient and creates an additional surgical step for
the surgeon. Moreover, this additional surgery causes additional bleeding
and as a consequence, creates an obstruction to the vision of the
surgeon. In order to cure the obstruction, the surgeon must address this
problem through an electro cautery procedure.

[0005] Also apparent to one skilled in this technology is that the
pathological target within the patient is often not an equal distance
vertically and horizontally. Hence, a surgical procedure may require a
surgical approach that for ideal conditions, provides access that is more
vertical in orientation than lateral. Obviously, a cylindrical device as
has been heretofore available and as disclosed in U.S. Pat. No. 6,159,179
supra, which is equidistant from the axis, does not allow for this
approach. Thus, in a cylindrical cannula, in order to gain additional
vertical access the size of the cannula must be increased the same amount
in the lateral direction that it is in the vertical direction. Obviously,
the human spine's skeletal structure, i.e. lateral facets and medial
spinous process, restricts the amount of lateral space available. In a
cylindrical cannula, since a limitation of the lateral space that is
available to locate a retractor, the vertical space is likewise limited.
As a consequence, the cylindrical cannula limits the number of patients
who are candidates for minimally invasive spinal surgery necessitating
the more invasive type surgery with all of the problems associated
therewith. Hence, for a large segment of the patient population, the only
surgery available is the more destructive invasive muscle burning and
stripping approach. This invention addresses this problem and provides a
solution whereby the minimal invasive surgery is now possible which
otherwise was considered impossible to perform, unpractical or
unpredictable in terms of surgical success or long-term outcome.

[0006] The other aspect of this invention is the improvement to the system
claimed in U.S. Pat. No. 6,159,179, supra. In this patent, the depth of
the cavity at the location where the invasive procedure is being
performed is measured and the surgeon can then select from a kit or
inventory of different sized cannulas or retractors the desired size
required to perform the surgical procedure.

[0007] I have found that a solution to the problem noted in the immediate
above paragraphs is that I provide in one embodiment of this invention,
dilators and retractors that are configured other than in a cylindrical
shape, such as an ovoid, and that I provide different sizes to meet the
anatomical needs of a particular patient. By providing dilators and
dilator retractors made in accordance with this invention, these
instruments will be able to reach down between the facet joint and the
spinous process to gently part muscle tissue and come into closer contact
to the bony target. This will reduce or eliminate the need for the
surgeon to surgically remove otherwise valuable viable muscle tissue.
This will also reduce post-operative pain and inter-operative time
(fiddle). In addition to the above, this new design will allow surgeons
to address new pathologies in patients that previously would not have
been able to undergo a minimally invasive technique. To more fully
appreciate the importance of this invention a common example is discussed
immediately hereinbelow.

[0008] This example considers a patient with multilevel central canal
stenosis. To address this patient's pathology, the surgeon may need over
35 millimeters (mm) of vertical access. The typical lateral distance,
i.e., space between the spinous process and the facet joint, available at
the L4 lamina is 16 mm. A 16 mm cylindrical retractor would fit tightly
against the lamina but even with "wanding" (moving up and down) it would
restrict the surgeons ability to reach much more than the 16 mm in
vertical access. The only option that is available to the surgeon,
heretofore, is to utilize a cylindrical retractor. As explained above,
since the equation for a cylindrical retractor mandates that the lateral
and vertical expansions are equal, the cylindrical retractor would
quickly reach beyond the practical or acceptable size for many, if not
most, multilevel patient candidates.

[0009] Another embodiment of this invention is the contouring or
configuring of the bottom of the retractor in order to meet the
requirements of certain operation procedures and/or permit the retractor
to be positioned closer to the target. This invention contemplates
angling the tip in both a cylindrical and ovoid shaped retractor and/or
locating a tunnel in the bottom thereof which allows for a rod or implant
to be passed through the distal tip of the cannula and into a pedicle
screw.

[0010] While much has been accomplished in the medical field to limit
tissue disruption, use minimal incisions, reduce the hospital stay and
increase the speed in which the patient recovers, this invention is
intended to raise the surgical procedure to a higher level. This
invention in the field of minimally invasive surgery is particularly
efficacious in performing such spinal medical procedures as laminotomy,
medial facetectomy, foraminotomy, nerve root retraction, discectomy and
the like.

[0011] As discussed in U.S. Pat. No. 6,159,179, supra, atypical procedure
in performing a lumbar discectomy is to advance a guidewire through a
small incision which is advanced to the inferior edge of the superior
lamina. A small incision is then made that extends either cranially or
caudally. A dilator is then inserted over the guidewire. Larger diameter
dilators are sequentially inserted over each other to increase the
opening into the body cavity. Typically the guide wire is removed after
the first dilator is installed and eventually the dilators are all
removed after the tubular retractor has been inserted over the largest of
the dilators. Once these procedures are accomplished, the retractor is
locked into position by a retractor clamp that is clamped to a retractor
clamping arm which is fixed to a rigid member such as the operating
table. This provides an unencumbered zone where the surgeon can perform
the medical procedure that was intended to be performed. According to the
present invention, the dilators, of course will now conform to the
configuration discussed above.

[0012] Instead of sizing the cannula to the largest depth that is
anticipated in the surgical procedure, the U.S. Pat. No. 6,159,179,
supra, teaches providing to the surgeon a series of different sizes in a
kit so that the surgeon can measure the depth of the cavity of the
patient and select the requisite size from the kit. Hence, the surgeon
measures the depth by measuring from the exterior of the cavity to the
most interior position in the cavity (inferior edge of the superior
lamina) and then selects, for example, either a 10 millimeters (mm), 20
mm, 30 mm, etc. as the situation requires. The dilator retractor will
also have the same cross sectional shape as the dilator, but it may have
a predetermined configuration at the distal end. This invention improves
the state of the art of spinal surgery by expanding the current
boundaries of minimally invasive surgery. This provides a new option to
patients that would otherwise be delegated to the more disruptive open
muscle stripping surgical approaches. The ovoid design with or without
the angled distal tip, allows a surgeon greater vertical access without
having to be encumbered by unnecessary lateral access.

[0013] Also, it is contemplated within the scope of this invention, that
the dilator retractor will be provided in a kit where a given
configuration will be provided in a series of dilator retractors that
have different lengths, so that the depth of the cavity of the patient
will determine the particular sized dilator retractor that will be
utilized for that procedure.

SUMMARY OF THE INVENTION

[0014] An object of this invention is to provide a cannula used in
minimally invasive technique that is tailored for a patient and
pathology.

[0015] A feature of this invention is to provide an ovoid shaped retractor
and a complementary shaped dilators. Other configurations that are not
cylindrical are contemplated within the scope of this invention.

[0016] Another feature of this invention is to contour the tip of the
distal end of the retractor to match the bone structure in the patient.

[0017] Another feature of this invention is to provide an access channel
at the distal end of the retractor to allow passage of medical hardware.

[0018] Another feature of this invention is to provide retractors that are
made from a series of predetermined sizes having tailored contouring that
the surgeon can select to match the depth of the cavity in the patient
made by the dilator.

[0019] The foregoing and other features of the present invention will
become more apparent from the following description and accompanying
drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a schematic illustration of the spine of a patient with
the cannula shown in cross section inserted adjacent to the posterior
portion of the vertebra and having superimposed the cannula resting on
the bone of a prior art configuration;

[0021] FIG. 2 is an exploded view in perspective of the non cannulated
dilator, a series of graduated increased diameter dilators and the
cannula or dilator retractor of this invention;

[0022] FIG. 3 is a view in perspective illustrating the non cannulated
dilator, the graduated dilators and the dilator retractor stacked over
each other as they would appear in the patient and the dilator retractor
shown in phantom when the other elements are removed;

[0023] FIG. 4 is a schematic illustrating an embodiment of this invention
where the dilator retractor is configured with the distal end being
slanted to accommodate the bone structure of the patient;

[0024] FIG. 5 is a schematic illustration exemplifying another embodiment
of this invention where the dilator retractor is configured with a tunnel
at the distal end;

[0025] FIG. 6 is a schematic illustration exemplifying another embodiment
of this invention where the dilator retractor is configured in a funnel
shape;

[0026] FIG. 7 is a photocopy of a drawing of the posterior view of the
3rd and 4th lumbar vertebrae with a schematic comparison of a
circular in cross section configured prior art dilator retractor and the
dilator retractor of this invention;

[0027] FIG. 8 is a schematic illustration of a series of different sized
dilator retractors sized to accommodate different lengths to fit the
anatomical dimensions of patients; and

[0028] FIG. 9 exemplifies another series of varying length dilator
retractors as would available to the surgeon.

[0029] These figures merely serve to further clarify and illustrate the
present invention and are not intended to limit the scope thereof.

DETAILED DESCRIPTION OF THE INVENTION

[0030] While the preferred embodiment of this invention is described
herein, it will be appreciated, as one skilled in this art will
recognize, that the invention although directed toward non-cylindrically
shaped dilator retractors, under certain circumstances, the invention
contemplates cylindrically shaped dilator retractors where the bottom or
distal end is configured to accommodate the shape of the bone structure
of the patient or to accommodate different procedures that are available
to the surgeon. As for example, the distal end of a cylindrically shaped
dilator retractor may be tunneled so as to allow the insertion of an
implant. The terms "cannula" and "dilator retractor" have the same
meaning and are used herein interchangeably. The term cavity as used
herein means the cavity that is created by the dilators and when the
dilator retractor is inserted in this cavity it becomes a working channel
for the surgeons use in performing the minimal invasive surgery. While
the invention is particularly efficacious for use in performing minimal
invasive surgery, as would be obvious to any skilled artisan, this
invention would also be useful for other types of surgery.

[0031] While in the preferred embodiment the description of this invention
details the use of a non cannulated dilator of the type described and
claimed in the Cross Reference of this patent application and which is
incorporated herein by reference, as one skilled in the art will
appreciate, this invention also contemplates the use of a guide wire for
certain surgical procedures.

[0032] To better understand this invention reference is made to the prior
art configuration of a dilator retractor as viewed in the target area of
a patient. In this example, the patient is inflicted with a herniated
disc in the spinal column and the surgeon targets the posterior portion
of the vertebra to perform the surgical procedure. The dilator retractor
or cannula 10 is inserted in the body and up to where the distal end
rests on the bone structure. Obviously, there is a space from left to
right between the bone and the end of the dilator retractor and as
mentioned above, tufts of muscle remains in or migrates to this area. The
surgeon needs to remove this material before performing the procedure for
repairing the herniated disc to the discomfort of the patient.

[0033] In accordance with one embodiment of this invention and as best
seen in FIGS. 2 and 3, a series of dilators 12, including the non-cannula
dilator 14 serve to enlarge the cavity of the patient by inserting the
first dilator or noncannula dilator 14 into a incision in the skin of the
patient and "working" the cannula dilator 14, a tool (not shown) engaging
the proximal end by forcing and rocking it through the fibrous and muscle
material until it reaches its target. The cannula dilator is an elongated
cylindrical solid body 16 having a tool engaging portion 18 at the
proximate end and a pointed tip portion 20 at the distal end. The tip 22
of the pointed tip portion is blunted and slightly rounded so that it is
unlike the tip of a common sewing needle, i.e. not razor sharp. The other
dilators 12, being progressively shorter in length are all similarly
constructed. Namely, they all are hollow so that each progressively
shorter dilator passes over the previously inserted dilator and have a
tool engaging end portion 24 at the proximate end and a beveled end
portion 26 at the distal end that fares into a sharp edge at the bottom
thereof. The dilators function is well known and for the sake of
convenience and brevity need not be detailed herein. The inventive aspect
of the dilators 12 is that they are configured in an elliptical or ovoid
shape in cross section and the circumferential dimension between the tool
engaging portion 24 and the beveled end portion 26. The hollow portion of
each of the dilators 18 are configured to complement the outer surface of
the preceding dilator and in the instance of the non cannula dilator 14,
the hollow portion of the next succeeding dilator 12 is circular in cross
section rather than being elliptical in cross section as are the next
succeeding dilators 12. After the dilators 12 have been inserted into the
patient, the dilator retractor 30 is inserted over the last inserted
dilator 12 and forced into position, typically with a template or anvil
that fits over the proximate end 32 of the dilator retractor 30. The
opposite end portion, similar to the dilators 12 is beveled and fares
into a sharp edge 34. The hollow portion or straight through bore 26 is
contoured identically to the contour of the preceding dilator 12. FIG. 3
demonstrates the positions of the dilators 12 and the non cannula dilator
14 when finally inserted into the patient. As seen in FIG. 3, the
dilators 12 and non cannula dilator 14 are removed leaving the dilator
retractor 30 in position. Obviously, the dilator retractor 30 affords a
wide channel for the surgeon to pass his instruments therethrough
allowing the surgeon to perform the surgical procedure while providing
sufficient opening to permit the use of a microscope and lighting to view
the area of the target.

[0034] As mentioned in the Background section of this patent application,
in accordance with this invention the distal ends of the dilator
retractors are "tailored" to meet certain criteria resulting from the
anatomical structure of the target area of the patient. FIGS. 4, 5, and 6
exemplify examples of what is meant by the term "tailoring" and while
these dilator retractors represent the preferred embodiment, it will be
understood by those skilled in this art that these are merely examples
and do not limit the scope of this invention. In FIG. 4, for example, the
distal end 40 of dilator retractor 42 is sloped to follow to some degree
the slope of the posterior portion of the vertebra. The direction of the
slope and the degree of the slope will be predicated on statistical
dimensions of these bone structure for a variety of different sized
individuals. The cross sectional configuration of the dilator retractor
42 can take any of a number of different shapes, such as elliptical,
circular, etc.

[0035] FIG. 5 is similar in concept to FIG. 4 except that the dilator
retractor 44 includes a cut-out portion 46 at the distal end 48 and side
50 is longer than side 52 or like the dilator retractor 42 depicted in
FIG. 4, the bottom portion can be sloped. Since the cut-out portion 46 is
made through the side walls and bore of the dilator and dilator retractor
it is essentially a cut out of the side walls at diametrical locations at
the distal end and hence, defines a lateral passageway or tunnel.

[0036] The dilator retractor 54 of FIG. 6 is similar to the dilator
retractor depicted in FIG. 4 except that the configuration is funnel
shaped. Namely, the upper portion 56 is conically shaped with the wider
portion at the proximal end and fares into the cylindrical portion 58.
The distal end 60 is sloped similar to the slope in the dilator retractor
42 depicted in FIG. 4. Obviously, the wider proximal end affords a wider
channel that is available for use by the surgeon.

[0037] It is apparent from the foregoing and particularly with the
embodiments depicted in FIGS. 4 and 5, the configuration of the dilator
retractors can take many shapes, namely cylindrical, elliptical or even
polygon shape. Of course, in the preferred embodiment, the thickness of
the wall over the major portion of the dilator retractors are uniform.

[0038] FIG. 7 is included to illustrate the comparison of the heretofore
known dilator retractors or cannulas and the dilator retractors or
cannulas made in accordance with certain embodiments of this invention.
FIG. 7 is a photocopy of a drawing of the lumbar vertebrae showing the
posterior view. If the surgeon requires an access provided by the dilator
retractor to be say, 35 mm, which is approximately 16 mm larger than the
current available dilator retractors, the cylindrically shaped dilator
retractor would have to be sized with a 35 mm diameter, as depicted by
the circle X. Obviously, this sized dilator retractor would not fit into
the contour of the vertebral body (spinous process) as it would be too
wide in the horizontal direction, although sufficiently wide in the
vertical direction. In accordance with this invention the major access of
the elliptically shaped dilator retractor illustrated by the oval Z is in
this example 35 mm and meets the requirement of the surgeon and the minor
axis or narrower portion fits into the channel defined by the bone
structure of this portion of the spine. In other words, the dilator
retractor is contoured to the anatomical configuration of the patient or
in other words is "tailored". It being noted that the 16 mm cylindrical
dilator retractor, although narrow enough in the horizontal direction, is
not sufficient in the vertical direction.

[0039] FIGS. 8 and 9 exemplify embodiments of this invention where the
particular "tailored" shape of the dilator retractor is provided in kits
of different lengths to match the depth of the cavity of the working area
of the patient. The kit may contain any number of sizes or alternatively,
a facility, like a hospital, may inventory a given number of sizes and
shapes of the dilator retractor. In the embodiment depicted in FIG. 8 a
series of different length dilator retractors or cannulas 70 with the
tunnel shaped distal end portion 72 are disclosed as a preferred
embodiment and in FIG. 9 a series of different length ovoid dilator
retractors 74 are depicted.

[0040] What has been shown by this invention is a novel, unique and
functional dilator retractor that is "tailored" to meet the anatomical
configuration of the patient. In addition, each of the configured dilator
retractors are sized so that they conform to the depth of the cavity in
which they are inserted into the patient. In addition to the benefits of
these configured dilator retractors that have been enumerated above,
these dilator retractors and the dilators associated therewith, afford
opportunities to the surgeon to operate in areas of the spine that were
not operable with minimal invasive surgery heretofore or at best were
operable with a given risk.

[0041] Although this invention has been shown and described with respect
to detailed embodiments thereof, it will be appreciated and understood by
those skilled in the art that various changes in form and detail thereof
may be made without departing from the spirit and scope of the claimed
invention.